Protective covers commonly referred to as "line guards" have been used by workmen working in an environment close to energized electrical conductors to cover adjacent conductors and associated hardware such as insulators on which the conductors are mounted to prevent the linemen or equipment from accidentally contacting the energized conductor causing hazardous shock and possibly death to the linemen. These prior and existing protective covers usually are formed of a relatively stiff dielectric material such as fiberglass and certain types of plastics. The covers are placed by various insulated devices in a suspended position on the conductor, insulator or the like while the workmen are in the vicinity of the conductor.
One common type of protective cover is an elongated tube having a spiral passageway extending from the exterior of the tube to a central space within the tube which assists in suspending the cover on a conductor to prevent it from blowing or being knocked off the line. Several examples of prior art conductive covers are shown in U.S. Pat. Nos. 2,770,667; 2,871,282; and 3,835,238. Other protective covers are placed over the insulator or cross arm on which the conductor is supported.
Although these prior protective covers perform satisfactorily for their intended purpose, it is desirable that the level of insulation protection be increased without increasing the size and weight of the cover. It is difficult for workmen to satisfactorily handle large diameter and heavy protective covers due to the need to handle the same at the end of the insulated rods or the like. Also, large covers are a problem due to the wind loads exerted thereon when suspended on an energized conductor or insulator. Existing covers for high voltage lines, for example 69,000 volts lines, do not provide adequate phase to phase protection due to the extremely large size that would be required to provide the insulating air space necessary to resist the electrical field stresses exerted about the conductor. Therefore, although existing conductor and insulator covers are satisfactory for many applications, it is preferable to provide a protective cover having increased insulation protection for the linemen without materially increasing the size and weight of the cover.
Another problem with certain of the existing protective covers which have a spiral passageway formed by spaced inner and outer walls is that when pressure is exerted against the outer wall or housing it can reduce the width of the insulating air space between the two housings or sleeves. This reduction seriously affects the level of insulation provided thereby possibly resulting in a flash-over of the conductor to a piece of equipment or workman contacting the outer housing of the protective cover.
Therefore, the need has existed for an improved protective cover for energized conductors, insulators or other such equipment which provides increased insulation and safety to a workman without materially increasing the size and weight of the cover.